Organic electronic devices play an important role in industry. For example, organic light emitting diodes (OLEDs) are promising for display applications due to their high power conversion efficiency and low processing costs. Such displays are especially promising for battery-powered, portable electronic devices, including cell-phones, personal digital assistants, handheld personal computers, and DVD players. These applications call for displays with high information content, full color, and fast video rate response time in addition to low power consumption.
OLED's typically contain organic electroluminescent (EL) material layers arranged between an anode and a cathode. Like other organic electronic devices, an OLED may contain other active materials such as buffer layers and charge transport layers. The EL materials can be small molecule materials, such as fluorescent dyes and organometallic complexes, or larger molecule materials, such as conjugated polymers and oligomers. Each EL or active material layer contributes to the overall performance of the display. Thus, when manufacturing an organic electronic device, such as a display containing an OLED, each active material layer such as the EL material, it can be very desirable to deposit the active materials in a controlled fashion onto a suitable underlying surface.
The EL material can be applied to the OLED from a liquid medium. The deposition of the organic EL material in the liquid medium can be accomplished using a continuous method, such as spin-coating, or a discontinuous method, such as ink jet printing. The deposition method should result in complete coverage of the desired area, in order to avoid current-leakage or shorting when the device is in operation. One area currently drawing the attention of researchers is the identification of methods for precise and optimum deposition of organic EL and other active materials from a liquid medium, which in turn results in cost-efficient production of devices containing OLED displays.